Every computer connected to the Internet is connected in some fashion to every other computer connected to the Internet, and all of these computers are capable of communicating with each other through various layers of network communications protocols. These protocols differ widely at the physical level. However, adverse activities can harm the packets during communications. To guarantee successful and secure communications, reliable methods for preventing risky network activities is necessary. Moreover, risky network activities (e.g., spams, virus, malware, etc.) nowadays are smart and adaptive, so intelligent methods to monitor and prevent the activities are desirable.